I’m Xiaoyu Yan, a data engineer focused on production data systems and data platform reliability.

Before data engineering, I spent years around biology, food science and engineering, epidemiology, and biostatistics. That background still shapes how I think about systems, evidence, and reliability.

This site collects generalized engineering field notes on production data systems: how complex pipelines fail, how migrations stabilize, and how reliable data platforms are built through contracts, boundaries, validation, and operational clarity.